Installing the Motherboard

With the motherboard populated,
the next step is to install it in the case. To do so, lower it into
place gently, verifying that each motherboard mounting hole has a corresponding
standoff installed and that no extra standoffs are present. Align the
motherboard rear I/O panel carefully with the I/O template, and slide the
motherboard into position. The threaded portion of each brass standoff should
be visible through the corresponding motherboard mounting hole, although you
may have to apply slight pressure toward the rear of the case to force
everything into alignment.

Note: The P160
includes several types of screws, including two types that appear to fit the
brass standoffs. In fact, only one of those types has the proper thread--the
one with slots for both Phillips and standard screwdrivers. The other type,
which requires a Phillips screwdriver, is intended for mounting optical drives and has a finer thread.

Install two or three screws
initially, but don't tighten them completely. Using the
available slack, force the other mounting holes into alignment and drive screws
into each of them. Once you have screws in each position (11, in the
case of the D925XCV), tighten all of them gently. Don't overtorque them, or you may crack the motherboard.

Once the motherboard is secure,
connect the front-panel switch and indicator cables, as shown in Figure 13. Do
the same for the front-panel FireWire, USB, and audio cables.

Figure 13. Connecting the front-panel cables

As we finished connecting the
front-panel cables, we noticed a loose cable with a Molex connector hanging
from the inside front of the case. As it turned out, this cable powers the LCD
temperature readout on the front of the case. We hadn't intended to use any
Molex devices in this system, so we hadn't installed the optional Molex power
cable when we assembled the Antec NeoPower 480 power supply. Fortunately, the jacks on the NeoPower
480 are readily accessible after the power supply is installed, so we simply
connected the Molex power cable to the power supply, as shown in Figure 14, and
connected one of the Molex plugs to power the front-panel display. Since we
were working in the vicinity, we connected the power supply fan control header
(the blue and black wires in Figure 14) to a fan power header on the
motherboard.

Figure 14. Adding a Molex cable to the NeoPower 480

The next step is to connect the
ATX12V main power cable, as shown in Figure 15. The D925XCV motherboard uses
the new 24-pin ATX12V connector rather than the traditional 20-pin connector.
You can use an older 20-pin ATX12V power supply with this motherboard, but if
you do, you should also connect a Molex connector from the power supply to the
Molex alternate power connector on the motherboard, visible in Figure 16

Figure 15. Connecting the ATX12V main power cable

Whatever you do, don't forget
to connect the ATX12V CPU power cable, as shown in Figure 16. If you fail to
connect this cable, the system won't boot. When the Pentium 4 was first
available, we forgot to connect this cable for the first half-dozen or so
systems we built. Now, it's so automatic for us to do so, we search
frantically for this connector on AMD Athlon XP and
other systems that don't use it.

Figure 16. Connecting the ATX12V CPU power cable

Prescott-core Pentium 4
processors such as the Pentium 4 560 run very hot, so providing adequate
cooling is essential. As Figure 17 shows, the processor in this system is
cooled by three large fans--the CPU fan itself, the
power supply fan, and a 120mm supplemental case fan. With all of those fan
blades spinning, it's important to make sure that no wires can foul the fans.
In particular, the CPU fan uses exposed blades and is very vulnerable to becoming entangled with a stray cable.

The placement of the ATX12V CPU
power cable makes it very likely to foul the CPU fan unless steps are taken to
prevent it. We considered routing that cable down low, near the motherboard,
but there wasn't any convenient way to secure the cable in that position.
Accordingly, we decided to secure the cable to part of the chassis frame with
twist ties, making sure that the cable was routed clear of the CPU fan and the
supplemental case fan. We also tucked in the CPU fan power cable, visible near
the bottom of the heat sink, to make sure it couldn't
foul the CPU fan.